Method and tools for repairing muffler assemblies



July 10, 1962 N. BROWN 3,043,002

METHOD AND TOOLS FOR REPAIRING MUFFLER ASSEMBLIES Filed Oct. 5, 1959 5Sheets-Sheet 1 w as Z -5- 64 42 4/. fijz.

54, A6 47 a6 44! 46 f7 58 52 54 4 2 36 4 i lA/l/EA/TO R1 LOWELL N. BROWNJu y 10, 1962 N. BROWN 3,043,002

METHOD 'AND TOOLS FOR REPAIRING MUFFLER ASSEMBLIES 3 Sheets-Sheet 2Filed Oct. 5, 1959 lAh flvrop: LOWEL z. N. BROWN,

H16 07- -0 RA/EYI y 1962 L. N. BROWN 3,043,002

METHOD AND TOOLS FOR REPAIRING MUFFLER ASSEMBLIES Filed 001;. 5, 1959 5Sheets-Sheet 3 38 26 I 38 F .22 j 60 62 I I l l P I ::::r

M r P m w: NTOR'. LOWELL N. meow/v,

H15 QTToEA/EV 3,643,982 Mnrnon ANB "roots FUR REPG MUFFLER AssnMnLmsLowell N. Brown, Overland, Mo. (9422 Trenton Ave, St. Louis 14, Mo.)Filed Get. 5, 1959, Ser. No. 844,376 Claims. (Cl. 29-401) The presentinvention relates generally to a method and means for repairing muffierassemblies of automotive vehicles.

More particularly, the present invention relates to a novel method and aset of tools adapted to facilitate and expedite the heretofore manuallyperformed operations required in the repair of mufiler assemblies.

A muffier assembly as contemplated herein includes a muffier proper, anexhaust pipe leading from the vehicle engine to the inlet end of themuffler, and a tail pipe leading from the outlet end of said mufiler toatmosphere.

Commonly, such assemblies are suspended immediately below the vehiclechassis by means of appropriate mufiler clamps and pipe hangers orbrackets. customarily as is well known, these assemblies are repairedfrom below, with the vehicle usually disposed on a hydraulic lift orover a pit. Working overhead with chisel and hammer, mechanism encountergreat difliculty particularly when the mufiler installation is so tospeak in a crowded location. In other Words, not only must they findSpace for the chisel, but also for the hand that holds the chisel.Furthermore, not only must they find space for the hammer itself, butalso additional space wherein to swing the hammer in attempting todirect effective blows against the chisel. Obviously, under conditionssuch as these, injuries to one or both hands of a mechanic frequentlyresult. Seldom also, is it possible to remove one component of theassembly without at least to some extent damaging the component theretoadjacent. Usually, when chisel and hammer operations prove inefiective,an acetylene torch will be employed to sever the components.

In addition to the hazards involved, the repair of muffier assemblies inaccordance with current practises comprise tedious and time-consumingundertakings, so-

that although it would seem that such operations are comparativelysimple, the time required to perform them heretofore has been excessive.

Accordingly, the primary object of the present invention is to provide amethod and means for overcoming the disadvantages referred to above.

To this end, the invention first of all teaches the employment of a setof novel tools that are mechanically operable, and that are contoured inaccordance with the concepts thereof. Three cutting tools are provided,and

each of them includes means whereby it may be operatively connected to aconventional pneumatic hammer as will appear. When so connected, each ofthe tools may be directed toward portions of the muffler assembly by themechanic holding the pneumatic hammer in one hand, so that as should beunderstood, the personal injury factor will thus be eliminated.Furthermore, the rapidity with which the pneumatic hammer would deliverits blows as compared with manually delivered blows beggars description,so that as should be manifest, the time factor involved will be greatlyreduced.

Another object of the invention is to incorporate means in said toolswhereby repairs may be effected by removal of a defective componentwithout more than negligible damage to an adjacent component that is tobe salvaged.

A further object of this invention is to teach a method whereby mufflerassembly repairs may be quickly made without the use of a torch or anyother means except the tools contoured in accordance with the conceptsthereof.

The invention is illustrated on three sheets of drawings 3,943,662Patented July 10, 1952 the accompany this specification, and a morecomprehensive understanding of its features and advantages may be hadfrom the detailed description that follows with reference to saiddrawings, wherein:

FIGURE 1 is a plan view of the cutofi chisel included in the set oftools provided by the present invention;

FIGURE 2 is a side elevational view of said chisel;

FIGURE 3 is a top plan view of the external cutter included in the setof tools provided by the present invention;

FIGURE 4 is a side elevational view of said cutter;

FIGURE 5 is a bottom plan view thereof;

FIGURE 6 is a transverse section, on an enlarged scale, taken on theline 66 of FIGURE 4;

FIGURE 7 is a transverse section, on an enlarged scale, taken on theline 77 of FIGURE 4;

FIGURE 8 is a fragmentary sectional view, on an enlarged scale, taken onthe line 8-3 of FIGURE 4;

FIGURE 9 is a top plan view of the internal cutter included in the setof tools provided by the present invention;

FIGURE 10 is a side elevational view of said cutter;

FIGURE 11 is a bottom plan view thereof;

FIGURE 12 is a transverse sectional on an enlarged scale, taken on theline 12-12 of FIGURE 10;

FIGURE'IS is a transverse section, on an enlarged scale, taken on theline I313 of FIGURE 10;

FIGURE 14 is a fragmentary sectional view, on an enlarged scale, takenon the line 14-14 of FIGURE 10;

FIGURE 15 is an exploded side elevational view of a typical pneumatichammer, and a complemental holder spring of beehive contour, wherewiththe tools of the present invention would be operatively connected to thehammer;

FIGURE 16 is a side elevational view illustrating a fragmentary portionof the barrel member of the hammer, with the shank of one of the toolsof the present invention operatively connected to the free end of saidbarrel by means of the beehive spring appearing in FIGURE 15, and saidspring being shown in section;

FIGURE 17 is a somewhat diagrammatic side elevational view of anexemplary standard automobile muffier assembly including a mufllerproper, an exhaust pipe leading from the engine to the intake end of themufller, and a tail pipe leading from the outlet end of said mufller toatmosphere, the mufiler clamps and the tailpipe hanger bracket servingto suspend the assembly from the chassis being suggested in brokenlines;

FIGURE 18 is a somewhat diagrammatic side elevational of anotherexemplary standard automobile muffler assembly including a muffierproper, an exhaust pipe leading from the engine to the intake end of themufiier, and a tail pipe leading from the outlet end of said mulliertoatmosphere, the mufiler clamps and the assembly from the chassis beingsuggested in broken lines;

FIGURE 19 is an enlarged reproduction, partly in section, of the outletend portion of the mufiler shown in FIGURE 17 and a fragmentary portionof the tail pipe leading therefrom, with the cutoff chisel of FIGURES land 2 being illustrated applied to said tail pipe;

FIGURE 20 is a sectional view taken on the line 2020 of FIGURE 19;

'FIGURE 21 is a view generally similar to FIGURE 19 illustrating theinitial step of applying the FIGURES 9 through 11 internal cutter toolto that segment of the tailpipe severed therefrom by thecutofi chisel;

FIGURE 22 is a view similar to FIGURE 21 illustrating the completion ofthe internal cutting tool operation;

FIGURE 23 is a sectional view taken on the line 23-23 of FIGURE 22;

FIGURE 24 is an enlarged reproduction, partly in section, of the outletend portion of the mufier ShOWn in FIGURE 18 and a fragmentary portionof the tailpipe leading therefrom, with the cutofif chisel of FIGURES 1and 2 being illustrated applied to the tubular extension FIGURE 25 is asectional view illustrating the initial step in the severance of themutfler extension from the adjacent end portion of the tailpipe thatextends'thereinto by means of the external cutter shown in FIGURES 3through 5;

FIGURE 26 is a view similar to'FIGURE 25 illustrating a more advancedstep in the severance of said rnuffler nal cutter tool;

FIGURE 30 is a view similar to FIGURE 28 with the cutoff chisel shownapplied to the tubular extension of the muffler; and

FIGURE 31 is a view illustrating the initial step in removing theextension segment from the tailpipe by means of the internal cuttertool.

With attention directed particularly to FIGURES 1 through 16, theinvention attains its objectives by means of a cutoif chisel generallydesignated 36, an external cutter generally designated 38, and aninternal cutter generally designated 40.

Ashereinbefore noted, each of these tools is designed to be power drivenby means of a pneumatically operable hammer of the gun type. Anexemplary hammer for the purpose is shown in FIGURE 15 anddesignatedI-I. It includes: a handle a repending from a cylindricalsection b; a flexible line leading to the hammer from a source ofcompressed air; a manually operable air pressure control device d; and abarrel e projecting from the cylindrical section b.

An appropriate mechanism for automatically reciproeating a pistonresponsive to manipulations of the control device d is located partiallyin the barrel e and partially in '-the cylindrical section b. However,it is not deemed necessary to illustrate and describe this pistonreciprocating mechanism, nor the air passageways associated therewith.Reference may be had if desired, to United States Letters Patent No.2,655,901 issued to me on October 20, 1953, for a comprehensivedisclosure of means for effecting reciprocal piston movements in theillustrated pneumatic hammer.

It will be understood of course that the pneumatic hammer H and itsoperating mechanisms form per se no part i of the present invention, andthat no claim is made herein to this particular hammer. In other words,whereas the invention contemplates a method requiring power-operatedtools, other conventional pneumatic hammers may be 7 employed to attainthe objectives thereof, if desired.

Formed externally in the free end portion 1 of the barrel e are a numberof annular grooves g that serve, with the aid of a suitable holderspring, to operatively connect the shank of a selected tool of thepresent invention to said barrel in position to receive hammer blowsdirected thereagainst by the reciprocating piston. An exemplary holderspring of the beehive type'appears in FIGURE l and is designated h. Bymeans of such spring or one of a similar nature, the cutoff chisel 36,the external cutter 38, and the internal cutter 40 may each beoperatively connected to the pneumatic hammer, as is well understood andis demonstrated in FIGURE 16. V

In saidview, numeral 42 designates thecaptive shank of any one of thetools 36, 38, or 40 of the present invention. In other words, the shanksof the three tools included in V the present invention are identical,each is designated by the same reference character, that being thenumeral 42, and each shank merges into an annular flange portiondesignated 44 that is adapted to be encompassed by the smaller coils ofthe holder spring h, with thelarger coils of said spring in engagementwith the grooves g of the barrel end f. g

With attention now focused on FIGURES 1 and 2, it will be seen that thecutoff chisel 36 includes, in addition to a shank 42 and an annularflange portion 44, a blade 46. The blade 46 is relatively thin as shown,and merges at one end into the cylindrical body portion 48 of thechisel, and said body portion in turn merges into the annular flange 44.The blade 46 flares outwardly on both sides thereof from thelongitudinal centerline of thechisel 36, and terminates at its free endin an arcuate sharp cutting edge 50. As will be apparent, the arcuateconfiguration of the cutting edge 50 prevents slipping of the chisel 36in operation. 7

With attention now focused on FIGURES 3 through 8, it will be seen thatthe external cutter 38 includes, in addition to a shank 42 and annularflange 44, a blade 52. The blade 52 is of the configuration shown, andmerges at one end into a cylindrical body portion 54 that in turn mergesinto the annular flange 44. The leading end of the blade terminates in agenerally V-shaped guide edge 56 that is comparatively thin, but notsharp enough to constitute a cutting edge. What will be considered thelower surface of the blade 52 is arcuately formed transversely thereofas indicated at 58. The leading end of the blade 52 has integrallyformed therewith an angularly upwardly projecting fin segment 69. Thefin segment 60 has a sharp cutting edge 62 that merges into the guideedge 56 as indicated at 64. As shown particularly in FIG- URE 8, thecutting edge 62 is preferably so formed that its apex lies along theinner surface of the fin segment 60 for a reason to appear.

7 With attention now focused on FIGURES 9 through 14, it Will be seenthat the internal cutter tool 40 includes, in addition to a shank 42 andflange 44, a blade 66. The blade 66 is of the configuration shown, andmerges at one end into a cylindrical body portion 68 that in turn mergesinto the annular flange 44. The leading end of the blade 66 terminatesin, a generally V-shaped guide edge 70 that is comparatively thin, butnot sharp enough to constitute a cutting edge. What will be consideredthe upper surface of the blade is arcuately formed transversely thereofas indicated at 72. The leading end of the blade 66 has integrallyformed there: with an angularly downwardly projecting fin segment 74.The fin segment 74has a sharp cutting edge 76 that merges into the guideedge 70 as indicated at 78. As shown particularly in FIGURE 14, thecutting edge 76 is so formed that its apex lies along the outer surfaceof the fin segment 74, for a reason to appear.

It will be remembered that all three tools illustrated and described areoperable by the pneumatic hammer H, so that as will be explained in moredetail hereafter,

. all cutting operations that would be necessary to repair mufllerassemblies may be made by connecting the appropriate one of said toolsto said hammer via the holder spring 11. It will also be understood thatwhen any one of the tools 36, 38, or 40 has been connected to the hammeras illustrated in FIGURE 16, the mechanic may point such toolin anydirection, and can manipulate the hammer to bring the blade thereof intonormally diificult-to-reac regions.

As hereinbefore observed, there are two types of muffler assemblies ingeneral use, and these are illustrated somewhat diagrammatically inFIGURES 17 and 18, where the mufiler proper is designated M.

' Inthe FIGURE 17 assembly, the mufller M is provided on each end with ahollow boss ortubular extension wherein the adjacent end portionsrespectively of the terminates within the inlet tubular extension 0, andone end of the tail pipe 17 terminates in the outlet tubular extensionr.

In the FIGURE 18 assembly, the muffler M is provided on each end with ahollow boss or tubular extension whereon the adjacent end portions ofthe associated exhaust pipe and tail pipe are mounted and terminate.-Thus, one .end portion of the exhaust pipe s leading from the engine ismounted on and terminates on the inlet extension I, and one end portionof the tail pipe u is mounted on and terminates on the outlet extensionv.

In explaining the methods of operation, it will first be assumed thatthe tailpipe p of the FIGURE 17 assembly had become defective for any ofvarious reasons, and that it were desirable to replace it while at thesame time salvaging the muffler M. With the cutofi chisel 36 connectedto the hammer H, the mechanic would first sever the left hand halfsection of the pipe p (as viewed in FIGURE 20) by directing the arcuatecutting edge 50 thereto from below, manipulating the control device d,and advancing the chisel upwardly in a generally perpendicular directionas should be understood from an inspection of said figure. Thereupon,this operation would be repeated on the right hand half section of thepipe, thus completing severance of the segment w (appearing also in FIG-URE 21) from the balance of the tail pipe p which would now bediscarded. Next, the mechanic would connect the internal cutter 4t) tothe hammer, and direct the guide edge 70 of said cutter as illustratedin FIGURE 21. Thereupon, while manipulating the control device d, hewould advance the cutter 40 leftwardly from the FIGURE 21 to the FIGURE22 position thereof, thus splitting the segment w longitudinally as thedisposition of the sharp cutting edge 76 deflects the sheared metalinwardly on one side of the cut. With the segment w thus slitlongitudinally from end to end and its circular wall thus deformed assuggested in FIGURE 23, withdrawal of the cutter 40 and removal of thesegment w from the extension r comprise easy and simple operations.

It is noted that the guide edge 70 serves to slightly separate thecontacting surfaces between the extension r and the pipe segment w, thusfacilitating the work of the cutting edge 76. At the same time however,the arcuate. upper surface 72 of the blade 66 prevents distortion of theextension r, so that following removal of the treated segment w, a newtail pipe may be quickly installed.

Obviously, should the exhaust pipe 11 of the FIGURE 17 assembly havebecome defective for any reason, and it were desirable to replace itwhile at the same time salvaging the mufiler M and tail pipe p, thedescribed steps would be taken at the inlet end of said muffler at theextension 0.

It will now be assumed that the mufller M of the'FIG- URE 17 assemblyhad become defective, and that it were desirable to replace it while atthe same time salvaging the exhaust pipe 11, and the tail pipe p. T 0this end, the extensions 0 and r would be severed from the mufiler; bodyby means of the cutoff chisel 36. This operation is demonstrated inFIGURE 24 with respect to the extension r, it being understood that theextension 0 would be treated in like fashion. In severing the saidextensions from the mufiler M, the cutoff chisel 36 would be manipulatedin the same manner as heretofore described and illustrated in FIGURE 20with respect to the tail pipe p.

Following severance of the extensions 0 and r, the muflier M would beremoved and discarded. Next the inlet and outlet muffler supportingclamps suggested in broken lines would be removed. Thereupon theexternal cutting tool 38, properly connected to the pneumatic hammer H(as should now be understood), would first be pointed as illustrated inFIGURE 25, with the guide edge 56 thereof directed toward the contactingsurfaces of the tail pipe p, and the severed muffler extension r. There:upon, while manipulating the control device d of the hammer H, themechanic would advance the cutter 38 rightwardly (as viewed in thedrawings) from the FIG- URE 25 position to the FIGURE 27 positionthereof, thus splitting the severed extension r longitudinally as the,disposition of the sharp cutting edge 62 deflects the sheared metaloutwardly on one side of the cut. .With the severed extension r thusslit longitudinally from end to end, and its circular wall thus spreadapart, withdrawal of the cutter 38 and removal of said extensioncomprise easy operations.

It should be apparent that the guide edge 56 serves to slightly separatethe contacting surfaces of the extension r and the end of the tail pipemounted thereon, thus facilitating the work of the cutting edge 62 asthe cutter 38 is advanced. At the same time however, the arcuate lowersurface 58 of the blade 52 prevents distortion of the tail pipe end, sothat following removal of said extension r (and removal of the extension0 from the end of the exhaust pipe s in similar fashion as should beunderstood), a new mufller could be quickly installed and the earlierremoved muffler supporting clamps aforesaid would again be placed inposition.

With respect to a mufiler assembly such as that appearing in FIGURE 18,it will first be assumed that the tail pipe u thereof had becomedefective and should be replaced, while at the same time it weredesirable to salvage the muffler M and the exhaust pipe s.

The method whereby such an operation would be accomplished in accordancewith the teachings of the present invention is demonstrated in FIGURES28 and 29. It is believed that in contemplation of the explanationhereinbefore presented, it should be manifest how the segment x afterbeing severed from the tail pipe u by means of the cutoff chisel 36, maybe quickly removed from the extension 1 following employment of thecutter 33.

In other words as a comparison of FIGURES 25 and 29 will demonstrate,the directional advances of the cutter 38 though opposite, would attaina similar result. It will further be apparent that subsequent to theoperation demonstrated in FIGURE 28, and consequently prior to theoperation demonstrated in FIGURE 28, and consequently prior to theoperation demonstrated in FIGURE 29, the outlet end mufiler clamp willhave been removed.

Assuming now with respect to the FIGURE 18 assembly that the mufller Mthereof had become defective and should be replaced by a newcounterpart, the method whereby this may be accomplished is portrayed inFIG- URES 30 and 31 as pertaining to the outlet end of said muffler, itbeing deemed obvious that corresponding treatment would be accorded theinlet end thereof.

In contemplation of the foregoing description and operationalexplanation augmented by the comprehensive illustrations presented inthe drawings, it is believed that an adequate understanding of thepresent invention should be had without further elaboration thereon. Inpractise it has been found that by means of the present invention, thetime heretofore required in manual chisel and hammer operations forrepairing mufiier assemblies has been greatly reduced. Furthermore, bymeans of the present invention, a novel method has been provided thatreduces personal injuries to a minimum.

Although primarily designed for use in repairing muffier assemblieswithout removing them from the vehicle chassis, it should of course bemanifest that a removed mufller assembly would still further reduce thetime required to effect any of the operations described.

What I claim is:

1. The method of removing a defective tail pipe from the muffler properof an automative vehicle mufller' assembly of the type wherein one endportion of the tail pipe terminates within the outlet tubular extensionof the mufiler, said method comprising: the steps of first operativelyconnecting a cutoff chisel having a thin blade provided with an arcuatecutting edge to the barrel of a pneumatic hammer of the characterdisclosed; thereupon projecting fin segment having a sharp cuttingedgethat merges into the guide edge aforesaid; thereupon slitting thesegment of tail pipe remaining in' said extension longitudinally fromend to end thereof by means of said internal cutter; thereuponwithdrawing the cutter; and

then removing said longitudinally slit segment from the tubularextension aforesaid. p

2. The method of removing a defective exhaust pipe from'the mufiilerproper of an automotive vehicle mufiler assembly of the type wherein oneend portion of the exhaust pipe terminates within the inlet tubularextension of the mufller, said method comprising: the steps of firstoperatively connecting a cutoff chisel having a thin blade provided withan arcuate cutting edge to the barrel of a pneumatic hammer of thecharacter disclosed; thereupon severing said exhaust pipe along animaginary line removed a short distance from said extension by means ofsaid chisel; thereafter removing said chisel from the hammer, and, thenoperatively connecting an internal cutter having a blade wit-han arcuateupper surface to the barrel of the same pneumatic hammer, said bladeterminating at its free end in a generally V-shaped guide edge, andbeing provided with an integral angularly downwardly projecting finsegment having a sharp cutting edge that merges into the guide edgeaforesaid; thereupon slitting the segment of tail pipe remaining in saidextension longitudinally from end 'to end thereof by means of saidinternal cutter; thereupon withdrawing the'cutter; and

then removing said longitudinally slit segment from the tubularextension aforesaid.

3. The method of removing a defective muffler proper from an automotivevehicle mufiler assembly of the type wherein one end portion of theexhaust pipe terminates withintthe inlet tubular extension, and one endportion of the tail pipe terminates within the outlet tubular extheadjacent ends of said pipes by means of said chisel;

thereafter removing said chisel from the hammer and then operativelyconnecting an external cutter having a blade with an arcuate lowersurface to the barrel of the same jpneumatic hammer, said bladeterminating at its free end in a generally V-shaped guide edge, andbeing provided'with an integral upwardly projecting fin segment having asharp cutting edge that merges into the guide edge aforesaid; thereuponwith the muffler removed, slithammer and then operatively connecting anexternal cutter having a blade with an arcuate lower surface to thebarrel of the samepneumatic hammer, said blade terminating at its freeend in a generally V-shaped guide I edge, and beingprovided with anintegral angularly upwardly projecting fin segment having a'sharpcutting edge that merges into the guide edge aforesaid; thereuponslitting the segment of tail pipe remaining on said extensionlongitudinally from end to end thereof by means of said cutter; andthereupon removing said longitudinally slit segment from the tubularextension aforesaid.

5. The method of removinga defective exhaust pipe from the mufllerproper of an automotive vehicle mufiier assembly of the type wherein oneend portion of the exhaust pipe terminates and is mounted on the inlettubular extension of the mufller, said method comprising: the

7 steps of first operatively connecting a cutoff chisel having a thinblade provided with an arcuate cutting edge to the barrel of a pneumatichammer of the character disclosed;

thereupon severing saidexhaust pipe along an imaginary line removed ashort distance from said extension by means of said chisel; thereafterremoving said chisel from the hammer and then operatively connecting anexternal cutter having a blade with an arcuate lower surface to thebarrel of the same pneumatic hammer, said blade terminating at its freeend in av generally V-shaped guide edge, and being provided with anintegral angularly upwardly projecting fin segment having a sharpcutting edge that merges into the guide edge aforesaid; thereuponslitting the segment of exhaust pipe remaining on said extensionlongitudinally from end to end thereof by means of said cutter; andthereupon removing said longitudinally slit segment from the tubularextension aforesaid. a a

6. The method of removing a defective muffler proper from an automotivevehicle mufiler assembly of the type wherein one end portion of theexhaustpipe terminates and is mounted on the inlet tubular extension,and one end portion of the tail pipe terminates and is mounted on theoutlet tubular'extension of the muffler aforesaid, said methodcomprising: the steps of first operatively connectting the segment'ofthe inlet tubular extension remaining on the adjacent end of the exhaustpipe and the segment of the outlet extension remaining on the adjacentend of the tail pipe longitudinally from end to end by means'of saidcutter; and thereupon removing the split extension segments respectivelyfrom the adjacent end of the exhaust pipe and the adjacent end of thetail pipe.

4. The method of removing a defective tail pipe from the mufiler properof an automotive vehicle muffler assembly of the type wherein one endportion of the tail pipe terminates and 'is mounted on the outlettubular extension of the muffler, said method comprising: the stepsof'first operatively connecting a cutoff chisel having a thin bladeprovided with an arcuate cutting edge to the barrel I of a pneumatichammer of the character disclosed; thereing a cutoff chisel having athin blade provided with an arcuate cutting edge to the barrel of apneumatic hammer of the character disclosed; thereupon severing each ofsaid extensions along an imaginary line removed a short distance fromthe adjacent ends of said pipes by means of said chisel; thereafterremoving said chisel from the hammer and then operatively connecting aninternal cutter having a blade with'an arcuate upper surface to thebarrel of the same pneumatic hammer, said blade terminating at its freeend in a generally V-shaped guide edge, and being provided with anintegral cutting edge that merges into'the guide edge aforesaid;thereupon With-the mufiier removed slitting the segment of the outlettubular extension remaining within the adjacent end portion of the tailpipe longitudinally from end to end thereof and slitting the segment ofthe inlet tubular extension remaining within the adjacent end portion ofthe exhaust pipe longitudinally from end to end thereof by means of saidcutter; and thereafter removing said longitudinally slit extensionsegments respectively from said adjacent end portion of the tail pipeand the exhaust pipe.

References Cited in the file of this patent 1 UNITED STATES PATENTS1,276,458

